"You can get a clean enough print to use, here's how. Get a piece of hardware cloth and suspend it 1" above the foil or paper you're going to print to. Place the cap on the hardware cloth and allow it to drop spores for a couple of hours until you can just see the spores on the print. Remove the cap and use the print. Do the above in a glovebox or tupperware container. Don't allow the cap to come in contact with the printing paper or foil at any time. If the cap is especially dirty, wash the top side of it with iodine, but be careful not to let any get on the gills."